Devices for precisely measuring fluid for various purposes are old in the art. Usually such devices are provided with stepper motors which are, of course, insensible to changes in ambient conditions such as temperature and pressure which, in turn, affect the viscosity of the fluid being metered. It is the purpose of this invention to provide a device for metering precisely measured quantities of fluid which will be independent of ambient conditions, which is of such simple construction as to enable discarding the metering component after one use which makes it especially attractive for medical purposes or for chemical processes where minute traces of a chemical would seriously affect the final use and, finally, to provide a device which can be readily adapted for the handling of fluids of different kinds, of different chemical compositions and viscosities, in large or small quantities and at high or low pressures.